HP-UX Workload Manager User's Guide

How WLM manages workloads
How WLM works
Chapter 3112
How WLM works
The following tasks outline how WLM works:
1. Sets initial resource allocations.
WLM sets resource allocations for your workloads based on metrics
for the workloads. When you first start WLM however, there are no
metrics for the workloads. So, WLM sets these initial allocations, in
terms of shares, as follows:
CPU shares: Each workload gets 1/n of the total CPU resources,
where n is the number of workloads
Memory shares: Each workload gets the default minimum memory
allocation (although the group can use more if needed)
Disk bandwidth shares: Are set as indicated in the configuration file
(if they are specified at all)
CPU shares are either relative or absolute. With relative shares, a
workload’s number of shares relative to the total number of shares
for all the workloads determines the group’s allocation. For example,
if group A has 50 shares and the other groups in the configuration
have 150 shares, group A has 50/200 or 25% of the CPU resources
(cores). With absolute CPU shares, 100 shares represent one core. So,
you only need to know how many shares a group has to determine its
allocation. For example, assume group A has 50 shares again. This is
an allocation of half of a core.
2. Accepts or calculates performance data.
For metric goals and shares-per-metric allocations, WLM accepts
metrics from data collectors. For usage goals and fixed allocations,
WLM calculates the metrics itself.
3. Compares performance data (reported performance) to stated goals
(desired performance) for each active goal-based SLO.
4. Determines new CPU allocations so that reported performance
converges on desired performance; also determines CPU allocations
to satisfy requests for shares-per-metric allocations and fixed
allocations.